1. Field of the Invention
This invention relates to a light weight air bag for use in the protection of occupants in an automobile from the automobile accident which develops excellent energy absorption performance and is capable of sufficiently preventing accidental breakage or the like due to local concentration of stress, excessive stretching and the like.
2. Description of Related Art
Within this technology, there is known an air bag disclosed, for example, in JP-A-7-291069.
Such an air bag is constructed by adhering a resin film to a portion of an elastomer film to regulate excessive expansion of the air bag made from the elastomer film to enhance the energy absorption performance. In this case, if the occupant moves suddenly into the developed air bag, the stretching of a portion of the elastomer film adhered with the resin film is controlled, while the remaining portion of the elastomer film not adhered with the resin film is stretched to absorb shock through impact.
In the conventional air bag made by locally adhering the resin film to the elastomer film, however, when the shock through impact is absorbed by the stretching deformation of the portion of the elastomer film not adhered with the resin film, a large stress concentrates in a position at a boundary between the adhered portion and the non-adhered portion of the resin film. This may result in a burst resulting from the implosion of the air bag at this position becoming high. Further, the total area of the stretching deformable elastomer film is small, so that the elastomer film is stretched over its stretching limit by the large impact action. Hence there is a possibility of breaking the air bag.
In addition, when the resin film is not adhered to the surface of the elastomer film located opposite to the occupants, the elastomer film is excessively stretched, so that when such a stretched elastomer film simply contacts with a slight protrusive portion of a constructional member located in a side of the vehicle body, these is a possibility of simply breaking the air bag.